one of my friends is 3 weeks late. she thinks shes pregnant.

hello,one of my friends is 3 weeks late for her period. she thinks she is pregnant but is not showing any signs.he has been a little stressed lately. she says she has always been on time with her periods. and has never been this late. she says that it i possible for females to skip periods but she still thinks that she is pregnant.is it true that wemon skip monts sometimes? she is 18. she said everytime she had sex it was with a condom.she never did it without one. is it possible she is pregnant? any help is appreciated.